Frequently asked

Yes — completely free and open source, released under the GNU GPL v3.0. There's no paid tier and nothing to unlock.

Seestar owners who want a finished image without learning a professional suite first. Nocturne walks you through the process one guided step at a time and explains the concepts as you go.

A stacked FITS master (.fit / .fits / .fts) — for example the file your Seestar produces after a session.

A 16-bit TIFF (.tif / .tiff) — a master you stacked in Siril, APP or DeepSkyStacker, or a picture you already finished elsewhere. Nocturne works out whether it is still unstretched, in which case the whole process applies, or already stretched, in which case it opens at the finishing steps. It tells you which it decided and lets you correct it in one click.

You can also point Nocturne at a folder of raw subs and let its built-in stacker grade and integrate them into a master first.

No — Nocturne opens an image and runs the whole pipeline with none of them. Two free ones are worth the ten minutes, though.

GraXpert (free) powers background/gradient extraction and one of the denoise options — recommended, and a quick install.

StarNet2 (free) separates stars from the rest of the image, which eleven of Nocturne's steps and tools depend on. The built-in fallback leaves about twice as much star flux behind, so this is the other one to install.

ASTAP (free) is optional — it adds plate-solving, target identification and annotation.

RC-Astro (paid) is entirely optional. Every step that can use it has a free fallback built in, so Nocturne is fully functional without it — it's simply a little better with it.

See Install & set up for exactly what to download and how to connect each one.

Yes, on any screen from 1280 × 800 up — on a Mac, that is the “Looks like” size in System Settings → Displays. On smaller screens some panels start folded, one click from open; the guide says what changes.

macOS on Apple Silicon (M1 or newer), Linux on x86-64 and Windows 11 on 64-bit PCs. The Linux build is made on Ubuntu 24.04, so it needs glibc 2.39 or newer. The Windows build is an installer, tested on Windows 11 Pro; Windows 10 has not been tried. There is no Intel-Mac build.

What Nocturne works with lists the telescopes, files and computers in one place.

Nocturne isn't notarized by Apple yet, so macOS refuses to open it the first time. Click Done, then go to System Settings → Privacy & Security, scroll down to Security, click Open Anyway and confirm with your password. You do this once for each new version.

The installer isn’t signed yet, so Windows may show Windows protected your PC. Click More info, then Run anyway. Each new version is a new unsigned file, so the warning comes back with every update.

On some new Windows 11 PCs a setting called Smart App Control is switched on. It may block unsigned programs without offering Run anyway; where it does, Nocturne cannot run until it is signed.

Nothing. All processing happens locally on your computer; Nocturne doesn't send your images anywhere. The only exceptions are things you choose to send: a stack you donate through Send a stack, an attachment on a problem report, or a finished picture submitted to the gallery. A donated stack is used only to test and improve Nocturne and is never republished; a submitted picture is published, which is the point of submitting it. The privacy page covers each one.

On the session planner, possibly. Each object the planner suggests has a card, and a card can carry a photograph of that object — chosen by hand from pictures already published on the gallery. So a picture accepted there might also illustrate its target. It is never automatic: I choose each one myself, and I use my own pictures where I can. It is the same picture, with the same handle and capture details, shown on another page of this site; nothing else about it is published. If you ask for a picture to come down, it comes down from both.

Plate-solving is optional — it's only needed for target identification, annotation, and photometric colour calibration. If you want it, install ASTAP and its D05 star database from the ASTAP page, then point Nocturne at ASTAP in Settings. Full steps are in Install & set up.

Your images stay on your computer unless you send one. Nocturne opens, processes and exports everything locally. There is no account and no cloud, and nothing is uploaded on its own.

Nocturne makes at most five network requests. Two can happen without you doing anything, and you can switch both off:

1. An update check, until you switch it off. At startup it asks github.com whether a newer version has been released. Your IP reaches GitHub as part of that request, as it does for any web request; I receive nothing from it. You can turn it off in Settings.
2. Usage counting, only if you say yes. Nocturne asks once, on first run. If you agree, it sends {"event": "daily", "version", "id"} once a day and nothing else. The id is a random number for your installation that changes every month, and no IP address is stored. If you decline, nothing is ever sent and you are not asked again.

The other three happen only when you ask for them:

3. Looking up star colours, when you calibrate colour that way. The Colour step offers two settings. Sky balance does the whole job on your computer. Photometric (SPCC) instead measures your picture against the catalogued colours of the stars in it, so it has to ask which stars those are. It sends the position and size of your patch of sky, never the picture, to VizieR, the astronomical data centre in Strasbourg. If you would rather it didn’t, use Sky balance.
4. Sending a picture to the gallery, only when you choose to. The Export step can publish a finished picture to the gallery. It never happens on its own: you tick a box and press a button, for that one picture. Your location is never sent, nothing appears until it has been looked at, and a published picture can be taken down by asking.
5. Sending a problem report, only when you press Send. Help ▸ Report a problem fills in Nocturne's version, your system and a diagnostic log (what Nocturne did, the tools it called and any errors), and shows you all of it before anything leaves. You can read the log, edit the rest, and untick the log entirely. Reporting from the website instead sends no log at all.

Why count usage at all? Downloads don’t show whether anyone actually uses the app, and that decides whether things like a proper support system are worth building. The full detail, including what is deliberately not collected, is on the privacy page.

It is designed for ZWO Seestar telescopes and tuned on the S30 Pro. It recognises the S30 Pro, S50 Pro and S50 from their own files. The original S30 has not been tested; its files should still work, because the image scale is read from each file. Nocturne can also process many one-shot-colour and dual-band stacked FITS files from other instruments. What Nocturne works with has the details.